THERMOCAPILLARY CONVECTION DURING FLOATING-ZONE SILICON GROWTH WITH AUNIFORM OR NONUNIFORM MAGNETIC-FIELD

Numerical solutions are presented for the thermocapillary convection d uring the floating-zone growth of silicon crystals with a steady, exte rnally applied magnetic field. Three floating-zone shapes are treated: the ''barrel shape'' corresponding to growth in microgravity, the ''b ottle shape'' corresponding to terrestrial growth without an induction coil, and a ''necked shape'' corresponding to growth with a radio-fre quency induction coil. The magnetic field is either uniform and axial, or it is non-uniform and axisymmetric. Two non-uniform fields are con sidered. The results for the bottle shape with a uniform magnetic fiel d help explain recent experimental results presented by Croll et al. [ J. Crystal Growth 137 (1994) 95]. The results for the non-uniform fiel ds show how the radial dopant non-uniformities in these experimental r esults can be avoided. The results for the barrel shape and for both u niform and non-uniform magnetic fields point to the benefits of combin ing microgravity and a magnetic field.